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 Table of Contents  
ORIGINAL ARTICLE
Year : 2021  |  Volume : 8  |  Issue : 1  |  Page : 9-14

CT chest interpretation of novel coronavirus disease (COVID-19): Our experience with the first 60 patients at MGM Medical College, Aurangabad, India


Department of Radiodiagnosis, MGM Medical College and Hospital, N6, CIDCO, Aurangabad, Maharashtra, India

Date of Submission01-Sep-2020
Date of Decision26-Nov-2020
Date of Acceptance26-Nov-2020
Date of Web Publication16-Mar-2021

Correspondence Address:
Dr. Bano Nikhat
Department of Radiodiagnosis, MGM Medical College and Hospital, N6, CIDCO, Aurangabad, Maharashtra.
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mgmj.mgmj_78_20

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  Abstract 

Introduction: In December 2019, the outbreak of a novel corona virus infection occurred in Wuhan City, China. Early discussions suggested that computed tomography (CT) should be the preferred modality for the diagnosis of COVID-19. However, the use of CT for COVID-19 diagnosis is controversial. Also, the detailed CT features of COVID-19 have been reported in only a small number of articles in the literature. Objective: To evaluate lung abnormalities on thin-section CT scans in patients with COVID-19. Materials and Methods: This study included the first 60 clinically suspected patients for COVID-19 infection. The patients have further investigated for COVID-19 infection by reverse transcription-polymerase chain reaction (RT-PCR) test and CT chest. We identified CT patterns suggestive of COVID-19 infection and calculated the total CT severity score. The imaging reports of the CT chest study were compared with the RT-PCR test results. Results: In our study, we had 37 male patients and 23 female patients. COVID-19 pneumonia was diagnosed in 55 of the 60 patients, but five patients did not show any commonly described findings of COVID-19 pneumonia. Of the 55 patients, the majority of them had ground-glass opacities. The bilateral lower lobes were involved in the majority of the cases. RT-PCR results show that, of the 60 patients, 37 were positive for COVID-19 and 23 were negative for COVID-19. The mean total lung severity score for the 60 patients was 11.5 (range, 0–25). Mediastinal lymphadenopathy was notably absent in all 60 patients and only five patients had traces of bilateral pleural effusion and only one patient had air trapping. In terms of the distribution of disease in the axial plane, peripheral distribution was found in most of the cases. The patients with higher CT scores required ICU admission and ventilator support, and had a poor prognosis. Conclusion: We found that chest CT may be useful as a standard method for the rapid diagnosis of COVID-19 to optimize the management of patients in hospital settings where nucleic acid testing kits are not available or available in limited quantities. Chest CT plays a crucial role in the early detection of COVID-19, particularly for those patients with a negative RT-PCR.

Keywords: Computed tomography, COVID-19, ground-glass opacities, RT-PCR


How to cite this article:
Nikhat B, Deshmukh M, Dahiphale DB, Mishrikotkar P S, Joshi S. CT chest interpretation of novel coronavirus disease (COVID-19): Our experience with the first 60 patients at MGM Medical College, Aurangabad, India. MGM J Med Sci 2021;8:9-14

How to cite this URL:
Nikhat B, Deshmukh M, Dahiphale DB, Mishrikotkar P S, Joshi S. CT chest interpretation of novel coronavirus disease (COVID-19): Our experience with the first 60 patients at MGM Medical College, Aurangabad, India. MGM J Med Sci [serial online] 2021 [cited 2021 Apr 14];8:9-14. Available from: http://www.mgmjms.com/text.asp?2021/8/1/9/311385




  Introduction Top


In December 2019, the outbreak of a novel corona virus infection occurred in Wuhan, City, China. In humans, corona viruses are among the spectrum of viruses that cause flu-like illnesses manifesting as common cold as well as a more severe respiratory illness—specifically, severe acute respiratory syndrome (SARS), which have mortality rates of 10%.[1],[2]

The novel corona virus was named SARS corona virus 2 (SARS-CoV-2) by the International Committee on Taxonomy of Viruses.[3] The disease can be spread through human-to-human contact and was declared a global public health emergency by the World Health Organization (WHO).

Reverse transcription-polymerase chain reaction (RT-PCR) requires many laboratory specifications and is time-consuming. Also, some patients with suspected COVID-19 may have initial RT-PCR test results that are false-negative for COVID-19 infection, which is harmful to the containment of the infectious disease. The diagnosis and treatment program (6th version) published by the National Health Commission of the People’s Republic of China[4] had defined the diagnosis of viral pneumonia based on radiologic features by radiologists as one of the diagnostic criteria for COVID-19. The CT sensitivity for accurate diagnosis of viral pneumonia is 98%,[5] which facilitates isolation and plays an important role in the management of patients with suspected SARS-CoV-2 infection. Early discussions suggested that CT should be the preferred modality for the diagnosis of COVID-19. However, the use of CT for COVID-19 diagnosis is controversial. Also, the detailed CT features of COVID-19 have been reported in only a small number of articles in the literature.[6],[7],[8]

We retrospectively analyzed the initial CT images of 60 patients with SARS-CoV-2 infection. We evaluated the CT studies to recognize the different CT chest patterns of COVID-19 to help to consult radiologists with possible CT findings of COVID-19 and enable a more effective response. Bilateral distribution of ground-glass opacities (GGO) with or without consolidation in lower lobes with peripheral subpleural predominance was the cardinal hallmark of COVID-19.[8],[9] However, with further analysis of increasing cases, a diversity of interesting CT imaging features was found, including crazy paving patterns, airway changes, reverse halo sign, etc..[10],[11],[12]

Ground-glass opacity

Ground-glass opacity (GGO) is defined as hazy areas with slightly increased lung density without obscuration of broncho vascular margins.[13] In patients with COVID-19, unilaterally, or bilaterally GGO with a peripheral basal subpleural predominance is commonly seen.[14],[15],[16] Moreover, GGO is often accompanied by other patterns, including reticular and/or interlobular septal thickening and consolidation.[15] GGO together with small areas of consolidation may suggest an organizing pneumonia pattern of lung injury.[17]

Consolidation

Consolidation refers to alveolar air being replaced by pathological fluids, cells, or tissues, manifested by an increase in the pulmonary parenchymal density that obscures the bronchovascular markings[13] Multifocal, patchy, or segmental consolidation distributed in subpleural areas is usually presented in COVID-19 patients.[12],[18],[19] Also, consolidation was considered as an indication of disease progression.

Air bronchogram

Air bronchogram is defined as a pattern of air-filled bronchi on a background of opaque (high-attenuation) airless lung[13] and was reported to be another CT manifestation of COVID-19.[14]

Subpleural bands

It is defined as a thin curvilinear opacity with 1–3mm thickness, lying less than 1cm from and parallel to the pleural surface.[13]

Vascular enlargement

Vascular thickening or enlargement is described as the dilatation of pulmonary vessels around and within the lesions on CT images representing swelling of the capillary wall caused by pro-inflammatory cytokines.

Reversed halo sign or atoll sign

The reversed halo sign, also known as the atoll sign, is focal GGO surrounded by a ring of consolidation.[13] It was initially reported to be specific for cryptogenic organizing pneumonia[20],[21] but was subsequently described in other infections too.[22] Recently, this sign was reported in several COVID-19 cases, which may be attributed to disease progression.[12],[23]

Lymphadenopathy

Thresholds for lymphadenopathy were somewhat arbitrary, typically 1cm in short-axis diameter for mediastinal nodes.[13]


  Materials and methods Top


This study was carried out at the Department of Radiology, MGM Medical College, and Hospital, Aurangabad, India. This study included the first 60 clinically suspected patients for COVID-19 infection presenting with acute onset febrile illness, flu-like symptoms, breathlessness, and reduced O2 saturation with positive contact history referred to the department of Radiology between May 5, 2020, and July 10, 2020. The patients have been further investigated for COVID-19 infection by RT-PCR test and CT chest.

Each lung lobe was studied to determine the extent affected by CT manifestations of COVID-19. Bilateral lungs were divided into five lung zones: left upper lobe, left lower lobe, right upper lobe, right middle lobe, and right lower lobe. Each lung lobe was assigned a score: score 0, 0% involvement; score 1, less than 5% involvement; score 2, 5% to less than 25% involvement; score 3, 25% to less than 50% involvement; score 4, 50% to less than 75% involvement; and score 5, 75%, or greater involvement.The total of all the scores provided the total CT severity score (maximal CT score, 25).

CT technique and image interpretation

Two CT scanners (TOSHIBA ACQUILION 128 AND 16 SLICE CT SCAN MACHINES) were used for all chest CT examinations. Conventional CT was performed with the patient in the supine position with the majority of the scans done during end-inspiration. Technicians who performed CT of patients with suspected COVID-19 were required to wear personal protective equipment. All axial CT images were reconstructed to 1-mm thin slices and multiplanar images which include sagittal and coronal reconstructions were obtained using the multiplanar reformatting technique on an Apple workstation, i.e., console using Osirix software.

Every chest CT examination was read first by two radiologists and the final reporting radiologists had 5–15 years of experience in interpreting chest CT. In patients with CT findings suggestive of viral pneumonia, the radiologists informed the respective consulting physician immediately. The physician would then order immediate isolation of the patient for clinical monitoring and treatment.

CT review

We viewed all chest CT examinations and corresponding images of patients in the cohort. We compared the time of the laboratory test result confirming a positive diagnosis of a virus and the time of the chest CT report confirming a positive diagnosis of viral pneumonia.

Approval for the retrospective study of patients with COVID-19 infection was obtained from the Institutional Ethical Review Board of MGM Medical College, Aurangabad, India.


  Results Top


In our study, we had 37 male patients and 23 female patients, with a mean age of 46 years (age range, 21–80 years). In our study of 60 patients, a total of 60 chest CT examinations had been performed.

Viral pneumonia was diagnosed in 55 of the 60 (91.66%) patients, but 5 (8.3%) patients did not show any commonly described findings of COVID-19 pneumonia [Table 1]. Fever (86%) and cough (58%) were most commonly seen [Table 2]. The bilateral upper lobes were involved in 27 of the 60 patients (45%), the right middle lobe was involved in 15 (25%), and bilateral lower lobes were involved in 53 (88.33%). Of the 60 patients, 52 (86%) had bilateral lung disease and 3 (5%) had exclusively unilateral lung disease [Table 3]. In terms of the distribution of disease in the axial plane, peripheral distribution was found in 35(58%) of the 60 patients, central distribution was found in 14 (23.33%) of the 60 patients, and diffuse distribution was found in 6 (10%) of the 60 patients [Table 3].
Table 1: RT-PCR and CT scan status

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Table 2: Biological and clinical profile

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Table 3: Pattern of distribution

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Of the 60 patients, 53 (88.33%) patients had lower lobe involvement, while 6 (10%) had diffuse lung involvement [Table 3]. The patients with higher CT scores required ICU admission, ventilator support, and had a poor prognosis [Table 4]. The mean total lung severity score for the 60 patients was 11.5 (range, 0–25).
Table 4: CT severity index

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Of the 60 patients, 5 (8.33%) had no GGO and no consolidation on CT chest scans but they had clinical symptoms and their RT-PCR tests were positive for COVID-19 pneumonia [Table 5]. Of the 55 patients with GGO, consolidation, or both, 28(46.66%) had only GGO (without consolidation) and zero (0%) had consolidation in the absence of GGO [Table 5].
Table 5: Predominant pattern of involvement

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Mediastinal lymphadenopathy was notably absent in all 60 patients and only 5 patients (8.47%) had traces of bilateral pleural effusion and only one (1.69%) patient had air trapping [Table 6].
Table 6: Morphological characteristics

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Of the 60 patients, 55(91.66%) showed pure ground-glass opacity in subpleural distribution [Table 6] [Figure 1].
Figure 1: A 47-year-old man with corona virus disease (COVID-19). Transverse CT scan shows multiple predominantly subpleural GGO and consolidation (black arrows)

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In these patients, 37 (61.66%) were positive and 23 (38%) were negative for COVID-19 by RT PCR.


  Discussion Top


In our study, viral pneumonia was diagnosed based on CT findings in 55 out of 60 (91.66%) patients with COVID-19. The treating physician prescribed isolation and supportive treatment in time for recovery in these 55 patients. The study shows that CT has a high accuracy that may be useful as a standard method for the diagnosis of COVID-19 and thus the use of CT for the diagnosis of viral pneumonia allows patients with suspected COVID-19 infection to be isolated, treated in time for recovery, thus optimizing patient management and preventing the spread of the pandemic.

Of the 60 patients in our COVID-19 cohort, only five (8.33%) did not have both GGO and consolidation. In our study, we observed that that GGO and consolidation were two major important most commonly seen findings on CT images of COVID-19.

The majority of the CT findings seen on the chest CT examinations of patients with COVID-19—peripheral subpleural GGO, consolidation, [Figure 1], vascular thickening [Figure 2], reverse halo/atoll sign [Figure 3], interlobular septal thickening [Figure 4], crazy paving [Figure 4], and air bronchogram[Figure 5] are the additional findings seen in COVID-19 pneumonia. Multifocal subpleural predominantly basal involvement was more common in our study. The patients with CT severity scores towards the higher side ranging from 20 to 25 had a poor prognosis and had a higher mortality rate.
Figure 2: A 50-year-old man with man with corona virus disease (COVID-19). Transverse CT scan shows multiple peripheral predominantly subpleural GGO and consolidation with vascular enlargement (black arrow) and sub pleural bands (white arrow)

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Figure 3: A 38-year-old woman with man with corona virus disease (COVID-19). Transverse CT scan shows reversed halo sign in right upper lobe (black arrow)

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Figure 4: A 68-year-old man with corona virus disease (COVID-19). Transverse CT scan shows GGO, inter- and intralobular septal thickening with crazy paving pattern on left side and consolidation

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Figure 5: A 62-year-old man with man with corona virus disease (COVID-19). Transverse CT scan shows multiple peripheral predominantly subpleural GGO and consolidation with air bronchogram (black arrow)

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  Conclusion Top


CT may be useful as a standard method for the diagnosis of COVID-19 based on CT features. Early diagnosis can lead to early control of the transmission of infection. CT is specifically useful in the diagnosis of COVID-19 in hospital settings lacking nucleic acid testing kits, thus helping the treating physician timely isolation of the patient and preventing the spread of the pandemic. However, CT chest cannot specifically identify the virus causing flu-like illness.

The clinical and CT features help clinicians to promptly evaluate the prognosis of patients with COVID-19 pneumonia.

Financial support and sponsorship

MGMIHS.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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